This application relates to devices for pivotally mounting lenses within the housing of an optical sighting device such as a riflescope and, in particular, to a pivoting lens unit that is pre-assembled prior to installing within the housing of the optical sighting device.
Optical sighting devices have long been used in conjunction with weapons, such as rifles and handguns, to allow a user to accurately aim the weapon. Optical sighting devices such as riflescopes typically include eyepiece and objective lenses positioned at opposite ends of a tubular housing. A lens assembly is positioned medially of the eyepiece and objective lenses, and may be movable along a longitudinal axis of the housing for adjustment of the optical power of the optical sighting device. An aiming reticle is positioned in the optical path of the optical sighting device, typically between the lens assembly and the eyepiece lens. Because bullet trajectory, wind conditions and distance to the target can vary depending upon shooting conditions, quality riflescopes typically provide compensation for variations in these parameters by allowing a user to make small adjustments to the optical characteristics or the aiming of the weapon relative to the rifle or handgun on which it is mounted. These adjustments are known as windage and holdover adjustments and are typically accomplished by pivotal movement of the lens assembly within the housing of the optical sighting device to divert the optical path of the observed light before it reaches the reticle, as shown in U.S. Pat. Nos. 3,297,389 and 4,408,842 to Gibson, which are incorporated herein by reference.
To aid in pivotal movement of the lens assembly, the optical sighting device industry has developed a pivoting lens unit and lens assembly, which includes a pivot cartridge mounted to the housing of the device, a pivot tube disposed within the housing and supporting the lens assembly, and a resilient member that biases the pivot cartridge toward the pivot tube while allowing pivotal movement of the pivot tube and lens assembly. In these designs, the pivoting lens unit is generally positioned proximate the eyepiece of the housing. However, it is also known to position the pivoting lens unit proximate the objective end of the housing. A pivot end of the pivot tube that extends along the longitudinal axis of the housing is pivotally mounted to the interior of the housing near the eyepiece end of the housing. The lens assembly is supported near a free end of the pivot tube opposite the pivot end. Adjustment of windage and holdover is accomplished by turning an adjustment mechanism that operatively engages a leaf spring, thereby driving the free end of the pivot tube, including the lens assembly, transversely of the housing longitudinal axis and thereby altering the optical path between the eyepiece and objective lenses.
However, current manufacturing and assembly processes require the pivoting lens unit to be manufactured and assembled with the housing. These processes are time-consuming and expensive because each component of the pivoting lens unit is manufactured and then separately assembled with the housing. The pivoting lens unit is provided on an xe2x80x9cas-needed basisxe2x80x9d and is typically manufactured and assembled by the same manufacturer at the same time the optical sighting device is built, thereby reducing flexibility in the manufacturing and assembly processes. In addition, the assembly process is complicated by the number of loose components that an installer must assemble in a particularized order. The process involves great efforts and requires substantial skill because the fit between components requires precise dimensional coordination, which is of substantial significance for the accurate operation of the optical sighting device. Imprecision of one component leads to re-manufacture and re-assembly of that component and possibly re-assembly of other components that followed in the assembly process.
The assembly process is further slowed and complicated by the requirement to use a special tool to assemble some components of the pivoting lens unit. The pivot tube is installed in the housing following installation of the leaf spring; however, to install the pivot tube, the installer must use a special hand tool to compress the leaf spring, which in final assembly is disposed between the housing and the pivot tube.
Thus, there exists a need to simplify the manufacturing and assembly processes associated with optical sighting devices, and the pivoting lens unit in particular, to reduce the costs of manufacturing and assembling a pivoting lens unit while maintaining or even improving the precision of optical sighting devices.
The present invention is directed in part to a pre-assembled pivoting lens unit that facilitates the manufacturing and assembly processes for an optical sighting device. Therefore, consistent with one aspect of the invention, a pre-assembled pivoting lens unit is disclosed that includes a pivot cartridge capable sized to be at least partially received by an optical sighting device housing, along with a pivot tube defining a first end movably coupled to the pivot cartridge and a second end extending from the pivot cartridge and capable of moving transversely to the longitudinal axis of the device housing. Disposed in the pivot tube between the first and second ends is a lens assembly capable of focusing an image when the lens unit is at least partially received by the device housing. A fastener such as a nut is used to pivotally secure the pivot cartridge to the first end of the pivot tube, and a resilient member such as a spring interposes the fastener and pivot tube first end to enable relative pivoting movement of the pivot tube.
Consistent with another aspect of the invention, the above-described lens assembly may be positionally fixed between the first and second ends of the pivot tube to provide an optical sighting device with fixed magnification. Alternatively, the lens assembly may include a cam sleeve supported around at least a portion of the pivot tube and communicating with the lens assembly to drive the lens assembly along the longitudinal axis, thereby selectively adjusting the optical magnification provided by the optical sighting device.
In another embodiment of the invention, the above-described lens assembly may include a key formed in the pivot cartridge that engages a keyway formed in the first end of the pivot tube, thereby restricting rotation of the pivot tube relative to the pivot cartridge and cam sleeve. Alternatively, the lens assembly may include a key formed in the housing that engages a keyway formed in the pivot cartridge for orienting and rotationally fixing the pivot tube about the housing longitudinal axis. Fixing the position of the pivot tube facilitates use of the cam sleeve for adjusting optical magnification.
Other aspects and embodiments of the present invention include an optical sighting device incorporating such a pre-assembled pivoting lens unit, as well as a method for manufacturing the same.
Pre-assembly of the pivoting lens unit in accordance with these aspects and features results in a cost-effective technique for producing the optical sighting device, since rather than tracking a series of components, the manufacturer need only track one componentxe2x80x94the pre-assembled pivoting lens unit. Moreover, consistent with an embodiment of the present invention, the entire pivoting lens unit can be pre-assembled at an off-site pre-assembly facility and shipped to the optical sighting device manufacturer as a single unit. Once the pivoting lens unit is pre-assembled, it can be pre-tested off-site or by the optical sighting device manufacturer before installing in the optical sighting device. Pre-assembly of the pivoting lens unit increases the availability of such units, for the unit can be manufactured, assembled, and tested separately from the optical sighting device and stored as an off-the-shelf item.
Further still, pre-assembling the pivoting lens unit in accordance with the disclosed embodiments of the invention simplifies the final assembly process and eliminates the need for special assembly tools to install the pre-assembled pivoting lens unit within the optical sighting device. In addition, the pre-assembled pivoting lens unit can be easily removed to expose components mounted within the optical sighting device for service or replacement as needed.
Additional aspects and advantages of this invention will be apparent from the following detailed description of particular embodiments thereof, which proceeds with reference to the accompanying drawings.